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Dendrocentric learning for synthetic intelligence

Abstract

Artificial intelligence now advances by performing twice as many floating-point multiplications every two months, but the semiconductor industry tiles twice as many multipliers on a chip every two years. Moreover, the returns from tiling these multipliers ever more densely now diminish because signals must travel relatively farther and farther. Although travel can be shortened by stacking tiled multipliers in a three-dimensional chip, such a solution acutely reduces the available surface area for dissipating heat. Here I propose to transcend this three-dimensional thermal constraint by moving away from learning with synapses to learning with dendrites. Synaptic inputs are not weighted precisely but rather ordered meticulously along a short stretch of dendrite, termed dendrocentric learning. With the help of a computational model of a dendrite and a conceptual model of a ferroelectric device that emulates it, I illustrate how dendrocentric learning artificial intelligence—or synthetic intelligence for short—could run not with megawatts in the cloud but rather with watts on a smartphone.

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Fig. 1: Demand of AI for flops is growing unsustainably.
Fig. 2: The energy a synthetic brain consumes could scale with its neurons like a biological brain.
Fig. 3: A short stretch of dendrite could detect a consecutive spike sequence.
Fig. 4: Concept for a dendrite-like nanoscale device and its 3D integration.

Code availability

The Mathematica notebook used to simulate and analyse the dendrite model is available  at https://web.stanford.edu/group/brainsinsilicon/documents/Spiny_Dendrite_Model.nb.

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Acknowledgements

This work was supported by US Office of Naval Research (grant numbers N000141310419 and N000141512827), US National Science Foundation (grant number 2223827), Stanford Medical Center Development (Discovery Innovation Fund), Stanford Institute for Human-Centered Artificial Intelligence (HAI), C. Reynolds and GrAI Matter Labs. I thank P. Sterling for his help editing the manuscript.

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K.B. conceived, performed and wrote up this work.

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Correspondence to Kwabena Boahen.

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K.B. is a co-founder and stockholder of Femtosense Inc. and an advisor to Radical Semiconductor.

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Supplementary Information

This file contains 3 sections: Energy per inference for GPT-3 on Pixel-4; Wiring analysis; and Dendrite model.

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Boahen, K. Dendrocentric learning for synthetic intelligence. Nature 612, 43–50 (2022). https://doi.org/10.1038/s41586-022-05340-6

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